Method for manufacturing semiconductor light emitting device and semiconductor light emitting device wafer

ABSTRACT

According to one embodiment, a method is disclosed for manufacturing a semiconductor light emitting device. The method can include forming a nitride semiconductor layer including a light emitting layer on a first substrate having an unevenness, bonding the nitride layer to a second substrate, and separating the first substrate from the nitride layer by irradiating the nitride layer with light. The forming the nitride layer includes leaving a cavity in a space inside a depression of the unevenness while forming a thin film on the depression. The film includes a same material as part of the nitride layer. The separating includes causing the film to absorb part of the light so that intensity of the light applied to a portion of the nitride layer facing the depression is made lower than intensity of the light applied to a portion facing a protrusion of the unevenness.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority fromthe prior Japanese Patent Application No. 2011-134969, filed on Jun. 17,2011; the entire contents of which are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to a method formanufacturing a semiconductor light emitting device and a semiconductorlight emitting device wafer.

BACKGROUND

A semiconductor light emitting device such as a laser diode (LD) andlight emitting diode (LED) is fabricated by, for instance, crystalgrowth of nitride semiconductor layers on a substrate made of e.g.sapphire or SiC.

In a semiconductor light emitting device, to achieve high light emissionefficiency and high reliability, it is desired to improve heatdissipation. There is a configuration in which a grown nitridesemiconductor layer is bonded to a substrate having higher heatdissipation than the growth substrate, which is then removed. In thisremoval step, the nitride semiconductor layer is prone to cracking andpeeling.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are schematic views illustrating one step of a methodfor manufacturing a semiconductor light emitting device according to afirst embodiment;

FIG. 2 is a schematic sectional view illustrating a semiconductor lightemitting device manufactured by a method for manufacturing asemiconductor light emitting device according to the first embodiment;

FIG. 3 is a flow chart illustrating the method for manufacturing asemiconductor light emitting device according to the first embodiment;

FIGS. 4A to 4D, 5A to 5C, 6A to 6C, and 7A to 7C are sequentialschematic sectional views illustrating the method for manufacturing asemiconductor light emitting device according to the first embodiment;

FIG. 8 is an electron micrograph image illustrating the method formanufacturing a semiconductor light emitting device according to thefirst embodiment;

FIGS. 9A to 9D, and 10A to 10C are sequential schematic sectional viewsillustrating a method for manufacturing a semiconductor light emittingdevice of a reference example;

FIG. 11 is a schematic sectional view illustrating an alternativesemiconductor light emitting device manufactured by the method formanufacturing a semiconductor light emitting device according to thefirst embodiment;

FIGS. 12A to 12C are schematic views illustrating members used in themethod for manufacturing a semiconductor light emitting device accordingto the first embodiment;

FIG. 13 is a schematic view illustrating a member used in the method formanufacturing a semiconductor light emitting device according to thefirst embodiment;

FIG. 14 is a schematic view illustrating a member used in the method formanufacturing a semiconductor light emitting device according to thefirst embodiment;

FIG. 15 is a flow chart illustrating a method for manufacturing asemiconductor light emitting device according to a second embodiment;and

FIG. 16 is a schematic sectional view illustrating a semiconductor lightemitting device wafer according to a third embodiment.

DETAILED DESCRIPTION

According to one embodiment, a method is disclosed for manufacturing asemiconductor light emitting device. The method can include forming anitride semiconductor layer including a light emitting layer on a majorsurface of a first substrate having the major surface provided with anunevenness having a depression and a protrusion. The method can includebonding the nitride semiconductor layer to a second substrate. Themethod can include separating the first substrate from the nitridesemiconductor layer by irradiating the nitride semiconductor layer withlight via the first substrate. The forming the nitride semiconductorlayer includes leaving a cavity in a space inside the depression of theunevenness while forming a thin film on an inner wall surface of thedepression of the unevenness. The thin film includes a same material asat least a part of the nitride semiconductor layer. The nitridesemiconductor layer includes a first portion facing the depression and asecond portion facing the protrusion. The separating includes causingthe thin film to absorb at least a part of the light so that anintensity of the light applied to the first portion is made lower thanan intensity of the light applied to the second portion.

According to another embodiment, a method is disclosed for manufacturinga semiconductor light emitting device. The method can include bonding anitride semiconductor layer of a workpiece to a second substrate. Theworkpiece includes a first substrate having a major surface providedwith an unevenness having a depression and a protrusion, the nitridesemiconductor layer provided on the major surface and including a lightemitting layer, a thin film provided on an inner wall surface of thedepression of the unevenness and including a same material as at least apart of the nitride semiconductor layer, and a cavity provided in aspace inside the depression. The nitride semiconductor layer includes afirst portion facing the depression and a second portion facing theprotrusion. In addition, the method can include separating the firstsubstrate from the nitride semiconductor layer by irradiating thenitride semiconductor layer with light via the first substrate. Theseparating includes causing the thin film to absorb at least a part ofthe light so that an intensity of the light applied to the first portionis made lower than an intensity of the light applied to the secondportion.

According to another embodiment, a semiconductor light emitting devicewafer includes a base member, a nitride semiconductor layer, and a thinfilm. The base member has a major surface provided with an unevennesshaving a depression. The nitride semiconductor layer is provided on themajor surface and includes a light emitting layer. The thin film isprovided on an inner wall surface of the depression of the unevennessand includes a same material as at least a part of the nitridesemiconductor layer. The nitride semiconductor layer forms a cavity in aspace inside the depression.

Various embodiments will be described hereinafter with reference to theaccompanying drawings.

The drawings are schematic or conceptual. The relationship between thethickness and the width of each portion, and the size ratio between theportions, for instance, are not necessarily identical to those inreality. Furthermore, the same portion may be shown with differentdimensions or ratios depending on the figures.

In the present specification and the drawings, components similar tothose described previously with reference to earlier figures are labeledwith like reference numerals, and the detailed description thereof isomitted appropriately.

First Embodiment

FIGS. 1A and 1B are schematic views illustrating one step of a methodfor manufacturing a semiconductor light emitting device according to afirst embodiment.

More specifically, FIG. 1A is a sectional view taken along line B1-B2 ofFIG. 1B. FIG. 1B is a sectional view taken along line A1-A2 of FIG. 1A.

As shown in FIGS. 1A and 1B, the method for manufacturing asemiconductor light emitting device according to the embodiment uses afirst substrate 50 (growth substrate) having a major surface 50 aprovided with an unevenness 50 u. On the major surface 50 a of the firstsubstrate 50 is provided a nitride semiconductor layer 10 s. The nitridesemiconductor layer 10 s includes a light emitting layer (not shown)described later. The portion of the nitride semiconductor layer 10 sfacing the first substrate 50 is made of e.g. a GaN layer.

The nitride semiconductor layer 10 s is bonded to a second substrate 70.In this example, the nitride semiconductor layer 10 s and the secondsubstrate 70 are bonded via an intermediate layer 75. Thus, it isassumed that the case where the nitride semiconductor layer 10 s and thesecond substrate 70 are bonded via a different layer is also included inthe case where the nitride semiconductor layer 10 s and the secondsubstrate 70 are bonded. Specific examples of the intermediate layer 75are described later.

The unevenness 50 u includes a depression 50 d and a protrusion 50 p. Asshown in FIG. 1B, in this example, the protrusion 50 p is continuous,and a plurality of depressions 50 d are provided. In this case, asviewed along the axis perpendicular to the major surface 50 a, theprotrusion 50 p surrounds each of the plurality of depressions 50 d.

However, as described later, it is also possible that the depression 50d is continuous, and a plurality of protrusions 50 p are provided.

In the example shown in FIG. 1B, the planar shape of the depression 50 dis circular. The embodiment is not limited thereto. The planar shape ofthe depression 50 d (and the protrusion 50 p) is arbitrary.

A thin film 65 is provided on the inner wall surface of the depression50 d of the unevenness 50 u. The thin film 65 includes the same materialas at least part of the nitride semiconductor layer 10 s. In thisexample, the thin film 65 includes GaN. Furthermore, a cavity 50 cexists in the space inside the depression 50 d.

In the manufacturing method, the nitride semiconductor layer 10 s isirradiated with light Lr via the first substrate 50 to separate thefirst substrate 50 from the nitride semiconductor layer 10 s. Thisprocess may be referred to as laser lift-off process.

At least part of the light Lr is transmitted through the substrate 50and absorbed by the nitride semiconductor layer 10 s. The light Lr isbased on e.g. a KrF laser with a wavelength of 248 nanometers (nm). Thelight Lr is absorbed by the portion (GaN layer) of the nitridesemiconductor layer 10 s facing the first substrate 50, and the portionis decomposed. Thus, the first substrate 50 is removed from the nitridesemiconductor layer 10 s.

In this step, at least part of the light Lr is absorbed by the thin film65. Thus, the intensity of light applied to the portion (first portion61) of the buffer layer 60 facing the depression 50 d is made lower thanthe intensity of light applied to the portion (second portion 62) of thebuffer layer 60 facing the protrusion 50 p.

The second portion 62 is in contact with the protrusion 50 p. The secondportion 62 is irradiated with light having an intensity required forremoval. By irradiation with the light Lr, the GaN layer of the secondportion 62 is decomposed. On the other hand, even if the GaN layer ofthe first portion 61 irradiated with light having low intensity is notdecomposed, the first portion 61 and the first substrate 50 areseparated from each other. Hence, by decomposition of the GaN layer ofthe second portion 62, the first substrate 50 is removed from thenitride semiconductor layer 10 s.

In the embodiment, the intensity of light applied to the first portion61 of the nitride semiconductor layer 10 s is low. This suppressesoverall damage to the nitride semiconductor layer 10 s.

The embodiment can provide a semiconductor light emitting device inwhich damage to the semiconductor layer (nitride semiconductor layer 10s) in removing the growth substrate is suppressed.

Here, as shown in FIGS. 1A and 1B, the axis perpendicular to the majorsurface 50 a is defined as Z-axis. One axis perpendicular to the Z-axisis defined as X-axis. The axis perpendicular to the Z-axis and theX-axis is defined as Y-axis.

In the following, one example configuration of the semiconductor lightemitting device manufactured by the manufacturing method according tothe embodiment is described.

FIG. 2 is a schematic sectional view illustrating the configuration of asemiconductor light emitting device manufactured by the method formanufacturing a semiconductor light emitting device according to thefirst embodiment.

As shown in FIG. 2, the semiconductor light emitting device 110manufactured by the manufacturing method according to the embodimentincludes a first electrode (e.g., n-side electrode 10 e), a secondelectrode (e.g., second substrate electrode 70 e), and a nitridesemiconductor layer 10 s. The nitride semiconductor layer 10 s isprovided between the first electrode and the second electrode.

The first electrode (e.g., n-side electrode 10 e) includes e.g. a firstconductive layer 11, a second conductive layer 12, and a thirdconductive layer 13. The second conductive layer 12 is provided betweenthe first conductive layer 11 and the nitride semiconductor layer 10 s.The third conductive layer 13 is provided between the second conductivelayer 12 and the nitride semiconductor layer 10 s.

The first conductive layer 11 is made of e.g. Au. The second conductivelayer 12 is made of e.g. Al. The third conductive layer 13 is made ofe.g. Ti. The embodiment is not limited thereto. The material used forthe first conductive layer 11, the second conductive layer 12, and thethird conductive layer 13 is arbitrary. Furthermore, the first electrodemay have a stacked layer structure of four or more layers. For instance,the first electrode may have a four-layer structure of Ti layer/Allayer/Ni layer/Au layer. Alternatively, the first electrode may have afive-layer structure of Ti layer/Al layer/Ta layer/Pt layer/Au.

The nitride semiconductor layer 10 s includes a first semiconductorlayer 10, a second semiconductor layer 20, and a light emitting layer30. The light emitting layer 30 is located between the first electrodeand the second semiconductor layer 20. The first semiconductor layer 10is located between the first electrode and the light emitting layer 30.

The first semiconductor layer 10 includes a nitride semiconductor andhas a first conductivity type. The second semiconductor layer 20includes a nitride semiconductor and has a second conductivity type. Thesecond conductivity type is different from the first conductivity type.For instance, the first conductivity type is n-type, and the secondconductivity type is p-type. The embodiment is not limited thereto. Thefirst conductivity type may be p-type, and the second conductivity typemay be n-type. In the following description, it is assumed that thefirst conductivity type is n-type, and the second conductivity type isp-type.

The first semiconductor layer 10 is made of e.g. GaN. The firstsemiconductor layer 10 is doped with impurity such as silicon (Si) andgermanium (Ge). The thickness of the first semiconductor layer 10 ise.g. approximately 4 micrometers (μm).

The first semiconductor layer 10 can include e.g. a plurality of n-typelayers. The first semiconductor layer 10 includes e.g. a first n-typelayer 10 a and a second n-type layer 10 b. The second n-type layer 10 bis provided between the first n-type layer 10 a and the light emittinglayer 30. The first n-type layer 10 a and the second n-type layer 10 bare made of e.g. GaN. The first n-type layer 10 a functions as e.g. acontact layer. The first n-type layer 10 a is in ohmic contact with thefirst electrode (e.g., n-side electrode 10 e). The impurityconcentration in the first n-type layer 10 a is higher than the impurityconcentration in the second n-type layer 10 b.

The light emitting layer 30 includes e.g. a plurality of barrier layers(not shown) and a well layer (not shown) provided between the pluralityof barrier layers. The light emitting layer 30 can have a single quantumwell (SQW) structure. In this case, the light emitting layer 30 includestwo barrier layers and a well layer provided between the barrier layers.For instance, the light emitting layer 30 can have a multiple quantumwell (MQW) structure. In this case, the light emitting layer 30 includesthree or more barrier layers and a well layer provided between each pairof barrier layers.

The well layer includes e.g. In_(x1)Ga_(1-x1)N (0.05≦x1≦0.5). Thebarrier layer includes e.g. GaN. In the case where the barrier layerincludes In, the In composition ratio in the Group III elements of thebarrier layer is lower than the In composition ratio (x1 describedabove) in the Group III elements of the well layer. Thus, the bandgapenergy in the well layer is made smaller than the bandgap energy in thebarrier layer. The thickness of the well layer is e.g. 1 nm or more and5 nm or less. The thickness of the barrier layer is e.g. 3 nm or moreand 15 nm or less.

The peak wavelength of light emitted from the light emitting layer 30 ise.g. 400 nm or more and 650 nm or less.

A multilayer structure (e.g., superlattice layer) may be providedbetween the first semiconductor layer 10 and the light emitting layer30. The multilayer structure includes a plurality of first films (e.g.,GaN films) and a plurality of second films (e.g., InGaN films)alternately stacked in the Z-axis direction.

The second semiconductor layer 20 includes e.g. GaN. The secondsemiconductor layer 20 is doped with impurity such as magnesium (Mg) andzinc (Zn). The thickness of the second semiconductor layer 20 is e.g.approximately 2 μm.

The second semiconductor layer 20 can include a plurality of p-typelayers. The second semiconductor layer 20 includes e.g. a first p-typelayer 20 a, a second p-type layer 20 b, and a third p-type layer 20 c.The second p-type layer 20 b is provided between the first p-type layer20 a and the light emitting layer 30. The third p-type layer 20 c isprovided between the second p-type layer 20 b and the light emittinglayer 30.

The third p-type layer 20 c is made of e.g. AlGaN. The third p-typelayer 20 c functions as e.g. an electron overflow suppression layer. Thefirst p-type layer 20 a and the second p-type layer 20 b are made ofe.g. GaN. The first p-type layer 20 a functions as e.g. a contact layer.The impurity concentration in the first p-type layer 20 a is higher thanthe impurity concentration in the second p-type layer 20 b. In the caseof using Mg as impurity, the impurity concentration in the first p-typelayer 20 a is e.g. 1×10²⁰ cm⁻³ or more and 9×10²¹ cm⁻³ or less.

In this example, the surface of the first semiconductor layer 10opposite to the light emitting layer 30 is provided with an unevenness(surface unevenness 10 u). The depth of the surface unevenness 10 u ise.g. 0.3 μm or more and 5 μm or less. The spacing along the axisperpendicular to the Z-axis between the tops of the surface unevenness10 u is e.g. 0.5 μm or more and 10 μm or less. The surface of the firstsemiconductor layer 10 provided with the surface unevenness 10 uconstitutes a light extraction surface.

In this example, the surface unevenness 10 u is provided in the portionof the surface of the first semiconductor layer 10 not covered with then-side electrode 10 e. However, the embodiment is not limited thereto.At least part of the region provided with the surface unevenness 10 umay be covered with the n-side electrode 10 e. The surface unevenness 10u may be provided on the entire surface of the first semiconductor layer10. The surface unevenness 10 u is e.g. a roughened surface. Byproviding a surface unevenness 10 u, the light extraction efficiency ofthe semiconductor light emitting device 110 is increased.

The thickness of the first electrode (e.g., n-side electrode 10 e) ispreferably twice or more the depth of the surface unevenness 10 u. Thisstabilizes the electrical connection between the first electrode and thefirst semiconductor layer 10.

The semiconductor light emitting device 110 can further include a secondsubstrate 70, a second semiconductor layer side electrode (e.g., p-sideelectrode 20 e), and a barrier metal film (e.g., first barrier metallayer 15). The second semiconductor layer side electrode is locatedbetween the second electrode (e.g., second substrate electrode 70 e) andthe nitride semiconductor layer 10 s. The barrier metal film is locatedbetween the second electrode (e.g., second substrate electrode 70 e) andthe second semiconductor layer side electrode. The second substrate 70is located between the second electrode (e.g., second substrateelectrode 70 e) and the barrier metal film.

The p-side electrode 20 e is in ohmic contact with the secondsemiconductor layer 20. The p-side electrode 20 e functions as e.g. anohmic contact electrode and a high reflection electrode. At least partof the light emitted from the light emitting layer 30 is reflected atthe p-side electrode 20 e and emitted outside from the light extractionsurface on the first semiconductor layer 10 side.

The p-side electrode 20 e is made of e.g. Ni. This can reduce thecontact resistance with the second semiconductor layer 20. The p-sideelectrode 20 e can be made of e.g. at least one of Ag and Al. This canprovide high reflectance.

The inventor has experimentally found that the p-side electrode 20 emade of a stacked film of a Ni layer and Ag layer and sintered (heattreated) at approximately 400° C. can achieve ohmic contact and highreflectance. In this case, the thickness of the Ni layer is set to bethin (e.g., 5 nm or less). The thickness of Ag is thicker than that ofthe Ni layer, and is set to e.g. approximately 200 nm.

The p-side electrode 20 e can include at least one of Pt, Ru, Os, Rh,Ir, and Pd. That is, the p-side electrode 20 e can be made of a platinumgroup element. Depending on the impurity concentration and heattreatment condition for the second semiconductor layer 20, metals otherthan Ni and Ag can also provide ohmic contact.

In this specific example, the width (length along the axis perpendicularto the Z-axis) of the p-side electrode 20 e is wider than the width ofthe second semiconductor layer 20. The embodiment is not limitedthereto. The relative relationship between the width of the p-sideelectrode 20 e and the width of the second semiconductor layer 20 isarbitrary.

The first barrier metal layer 15 can include e.g. a first layer 15 a, asecond layer 15 b, and a third layer 15 c. The second layer 15 b isprovided between the first layer 15 a and the p-side electrode 20 e. Thethird layer 15 c is provided between the second layer 15 b and thep-side electrode 20 e. The first layer is e.g. an Au layer. The secondlayer is e.g. a Pt layer. The third layer is e.g. a Ni layer. Theselayers are formed by e.g. evaporation. Alternatively, these layers maybe formed by sputtering.

The first barrier metal layer 15 has the function of e.g. suppressinginterdiffusion between the p-side electrode 20 e and the bonding layer73 described later.

The third layer 15 c is made of e.g. a metal having high adhesiveness tothe p-side electrode 20 e. The third layer 15 c is preferably made ofe.g. at least one of Ti and Ni. The second layer 15 b is made of amaterial having high functionality to suppress interdiffusion betweenthe p-side electrode 20 e and the bonding layer 73. The second layer 15b is preferably made of e.g. Pt. The first layer 15 a is made of a metalmiscible with the bonding layer 73. The first layer 15 a is preferablymade of e.g. at least one of Au and AuSn.

This configuration can provide high reflectance at the p-side electrode20 e and high bonding strength between the p-side electrode 20 e and thebonding layer 73.

The second substrate 70 includes a support substrate 71, a bonding layer73, and a second barrier metal layer 72. In the semiconductor lightemitting device 110, the bonding layer 73 is located between the supportsubstrate 71 and the nitride semiconductor layer 10 s. The secondbarrier metal layer 72 is provided between the support substrate 71 andthe bonding layer 73.

The support substrate 71 is an electrically conductive substrate. Thethermal conductivity of the support substrate 71 is higher than thethermal conductivity of the first substrate 50. The support substrate 71is made of e.g. Ge, Si, Cu, and CuW. This can provide electricalconductivity and high heat dissipation.

The thermal expansion coefficient difference between the first substrate50 and the support substrate 71 may cause large warpage. Large warpagemay result in breaking the support substrate 71 during the laserlift-off process. Thus, as the support substrate 71, it is preferable touse a Si substrate or Ge substrate compared with a metal substrate.Furthermore, in view of process compatibility in the singulation (chipformation) step, it is more preferable to use a Si substrate as thesupport substrate 71.

The second barrier metal layer 72 can include e.g. a fourth layer 72 a,a fifth layer 72 b, and a sixth layer 72 c. The fifth layer 72 b isprovided between the fourth layer 72 a and the support substrate 71. Thesixth layer 72 c is provided between the fifth layer 72 b and thesupport substrate 71. The fourth layer 72 a is e.g. an Au layer. Thefifth layer 72 b is e.g. a Pt layer. The sixth layer 72 c is e.g. a Nilayer. These layers are formed by e.g. evaporation. Alternatively, theselayers may be formed by sputtering.

The fourth layer 72 a can have the function of mixing with the bondinglayer 73. The fifth layer 72 b can have the function of e.g. suppressinginterdiffusion between the support substrate 71 and the bonding layer73. The sixth layer 72 c can have the function of increasing theadhesiveness between the support substrate 71 and the fifth layer 72 b.

The bonding layer 73 is located between the first barrier metal layer 15and the second barrier metal layer 72. The bonding layer 73 is e.g. anAuSn layer. The nitride semiconductor layer 10 s and the supportsubstrate 71 are bonded via the p-side electrode 20 e, the first barriermetal layer 15, the bonding layer 73, and the second barrier metal layer72.

The second substrate electrode 70 e is provided on the surface of thesecond substrate 70 opposite to the nitride semiconductor layer 10 s.That is, the second substrate 70 is located between the second substrateelectrode 70 e and the nitride semiconductor layer 10 s. The secondsubstrate electrode 70 e can be made of e.g. at least one of Ti, Pt, andAu. This can reduce the resistance between the second substrateelectrode 70 e and the second substrate 70 (specifically, the supportsubstrate 71 as a Si substrate). Thus, the operating voltage of thesemiconductor light emitting device 110 can be reduced.

By applying voltage between the first electrode (e.g., n-side electrode10 e) and the second electrode (e.g., second substrate electrode 70 e),a current flows in the light emitting layer 30 via the firstsemiconductor layer 10, the second semiconductor layer 20, the p-sideelectrode 20 e, the first barrier metal layer 15, the bonding layer 73,the second barrier metal layer 72, and the support substrate 71. Thus,light is emitted from the light emitting layer 30.

In this example, the semiconductor light emitting device 110 furtherincludes a protective layer 80. The protective layer 80 covers the sidesurface and part of the upper surface of the nitride semiconductor layer10 s.

The protective layer 80 is made of e.g. an insulating material such asSiO₂ and SiN. The protective layer 80 is provided on e.g. the sidewalland the outer peripheral portion of the nitride semiconductor layer 10 sexcept the light extraction surface. The protective layer 80 protectsthe side surface of the nitride semiconductor layer 10 s. In thisexample, the protective layer 80 is formed also on part of the uppersurface of the p-side electrode 20 e. The protective layer 80 thusprovided can suppress short circuit due to e.g. foreign matter attachedin the manufacturing process.

In this example, the semiconductor light emitting device 110 furtherincludes a translucent layer 85. The translucent layer 85 is provided one.g. the surface unevenness 10 u of the first semiconductor layer 10.The refractive index of the translucent layer 85 is lower than therefractive index of the first semiconductor layer 10. The refractiveindex of the translucent layer 85 is e.g. 1.6 or more and 2.5 or less.The thickness of the translucent layer 85 is e.g. 50 nm or more and 200nm or less. The transmittance of the translucent layer 85 for the lightemitted from the light emitting layer 30 is e.g. 90% or more. Thetranslucent layer 85 functions as e.g. a refractive index adjustmentlayer. This increases the light extraction efficiency.

In the following, one example of the method for manufacturing asemiconductor light emitting device according to the embodiment isdescribed. In the example described below, a plurality of semiconductorlight emitting devices 110 are fabricated from one first substrate 50.

FIG. 3 is a flow chart illustrating the method for manufacturing asemiconductor light emitting device according to the first embodiment.

FIGS. 4A to 4D, 5A to 5C, 6A to 6C, and 7A to 7C are sequentialschematic sectional views illustrating the method for manufacturing asemiconductor light emitting device according to the first embodiment.

As shown in FIG. 3, the method for manufacturing a semiconductor lightemitting device according to the embodiment includes a step for forminga nitride semiconductor layer 10 s on the major surface 50 a of a firstsubstrate 50 (step S110). The first substrate 50 has a major surface 50a provided with an unevenness 50 u. The nitride semiconductor layer 10 sincludes a light emitting layer 30.

More specifically, as shown in FIG. 4A, the major surface 50 a of thefirst substrate 50 is provided with an unevenness 50 u. The firstsubstrate 50 is made of e.g. sapphire or SiC.

On the major surface 50 a of the first substrate 50, a crystal of thenitride semiconductor layer 10 s is grown. This growth is based on e.g.the metal organic chemical vapor deposition (MOCVD) method. However, theembodiment is not limited thereto. The method for forming the nitridesemiconductor layer 10 s is arbitrary.

As shown in FIG. 4B, on the major surface 50 a, a buffer layer 60constituting part of the nitride semiconductor layer 10 s is formed. Thebuffer layer 60 includes a nitride semiconductor. The buffer layer 60 ismade of e.g. GaN. The thickness of the buffer layer 60 is e.g. 0.5 μm ormore and 5 μm or less.

The step for forming the nitride semiconductor layer 10 s (e.g., bufferlayer 60) includes leaving a cavity 50 c in the space inside thedepression 50 d while forming a thin film 65 on the inner wall surfaceof the depression 50 d of the unevenness 50 u. The thin film 65 includesthe same material as at least part of the nitride semiconductor layer 10s (e.g., buffer layer 60). The portion of the buffer layer 60 facing thedepression 50 d constitutes a first portion 61. The portion of thebuffer layer 60 facing the protrusion 50 p constitutes a second portion62. The second portion 62 is in contact with the protrusion 50 p.

As shown in FIG. 4C, a first semiconductor layer 10 is formed on thebuffer layer 60. A light emitting layer 30 is formed on the firstsemiconductor layer 10. A second semiconductor layer 20 is formed on thelight emitting layer 30. The nitride semiconductor layer 10 s includesthe buffer layer 60, the first semiconductor layer 10, the lightemitting layer 30, and the second semiconductor layer 20.

That is, as shown in FIG. 3, the formation of the nitride semiconductorlayer 10 s (step S110) includes forming a buffer layer 60 on the firstsubstrate 50 (step S111), and forming a first semiconductor layer 10 onthe buffer layer 60, forming a light emitting layer 30 on the firstsemiconductor layer 10, and forming a second semiconductor layer 20 onthe light emitting layer 30 (step S112).

Specifically, as the first semiconductor layer 10, for instance, a firstn-type layer 10 a and a second n-type layer 10 b are formed. The growthtemperature of the first semiconductor layer 10 is e.g. approximately1000° C. or more and approximately 1100° C. or less.

Subsequently, a barrier layer and a well layer constituting the lightemitting layer 30 are formed. The growth temperature of the lightemitting layer 30 is e.g. approximately 700° C. or more andapproximately 900° C. or less.

On the light emitting layer 30, for instance, a third p-type layer 20 c,a second p-type layer 20 b, and a first p-type layer 20 a constitutingthe second semiconductor layer 20 are formed. The growth temperature ofthe second semiconductor layer 20 is e.g. approximately 1000° C. or moreand approximately 1100° C. or less.

As shown in FIG. 3, on at least part of the second semiconductor layer20, a second semiconductor layer side electrode (e.g., p-side electrode20 e) is formed (step S115).

In this example, as shown in FIG. 4D, a p-side electrode 20 e is formedon part of the second semiconductor layer 20. For instance, as a p-sideelectrode 20 e, a Ni layer is formed on the second semiconductor layer20, and an Ag layer is formed on the Ni layer. The Ni layer and the Aglayer are formed by e.g. evaporation.

As shown in FIG. 3, on the second semiconductor layer side electrode, abarrier metal film (e.g., first barrier metal layer 15) is formed (stepS116).

Specifically, as shown in FIG. 5A, a first barrier metal layer 15 isformed on the p-side electrode 20 e and on the second semiconductorlayer 20. For instance, as a first barrier metal layer 15, a Ti layer(third layer 15 c) is formed, a Pt layer (second layer 15 b) is formedon the Ti layer, and an Au layer (first layer 15 a) is formed on the Ptlayer.

As shown in FIG. 3, the manufacturing method can further include a stepfor bonding the nitride semiconductor layer 10 s to a second substrate70 (step S120).

As shown in FIG. 5B, in the specific example, the second substrate 70includes a support substrate 71, a bonding layer 73, and a secondbarrier metal layer 72.

As shown in FIG. 5B, the bonding layer 73 of this second substrate 70 isbrought into contact with the first barrier metal layer 15 and heatedwhile applying a load on the first substrate 50 and the second substrate70. The load is e.g. 500 newtons (N) or more and 1000 N or less. Theheating temperature is e.g. 280° C. or more and 350° C. or less. Thus,the nitride semiconductor layer 10 s and the second substrate 70 arebonded.

In the embodiment, the thickness of the bonding layer 73 is preferablye.g. 2 μm or more. If the thickness of the bonding layer 73 is less than2 μm, there may be cases where a sufficient bonding strength cannot beachieved depending on the bonding condition. Insufficient bondingstrength may cause failure in the subsequent steps, or failure in thesemiconductor light emitting device.

In this example, the p-side electrode 20 e and the first barrier metallayer 15 are included in the intermediate layer 75 illustrated in FIG.1A. In the case where the second substrate 70 includes the supportsubstrate 71 with the second barrier metal layer 72 and the bondinglayer 73 provided separately from the second substrate 70, the secondbarrier metal layer 72 and the bonding layer 73 are further included inthe intermediate layer 75.

As shown in FIG. 3, the manufacturing method further includes a step forseparating the first substrate 50 from the nitride semiconductor layer10 s by irradiating the nitride semiconductor layer 10 s with light Lrvia the first substrate 50 (step S130).

More specifically, as shown in FIG. 5C, light Lr is applied to thesurface of the first substrate 50 opposite to the nitride semiconductorlayer 10 s. Thus, the first substrate 50 is separated from the nitridesemiconductor layer 10 s.

This separating step includes causing the thin film 65 to absorb atleast part of the light Lr so that the intensity of light applied to theportion (first portion 61) of the nitride semiconductor layer 10 sfacing the depression 50 d is made lower than the intensity of lightapplied to the portion (second portion 62) of the nitride semiconductorlayer 10 s facing the protrusion 50 p.

For irradiation with light Lr, for instance, a KrF laser is used. Theirradiation power density of the light Lr is e.g. 0.65 joules/squarecentimeter (J/cm²) or more and 0.80 J/cm² or less. However, theappropriate irradiation power density of the light Lr is optimallyadjusted depending on e.g. the area of the nitride semiconductor layer10 s, the in-plane intensity distribution of the laser beam, and thearea of the laser beam.

As shown in FIG. 6A, the first substrate 50 is separated from thenitride semiconductor layer 10 s. In the embodiment, the intensity oflight applied to the first portion 61 of the nitride semiconductor layer10 s is made lower. This suppresses damage to the nitride semiconductorlayer 10 s. That is, damage to the semiconductor layer in removing thegrowth substrate can be suppressed.

Subsequently, the following steps, for instance, for fabricating asemiconductor light emitting device are performed.

For instance, as shown in FIG. 6B, the buffer layer 60 is polished toexpose the first semiconductor layer 10.

More specifically, as shown in FIG. 3, after the above separating step(step S130), the manufacturing method according to the embodiment canfurther include a step for reducing the thickness of the nitridesemiconductor layer 10 s (step S140). Thus, the nitride semiconductorlayer 10 s becomes a stacked body of the first semiconductor layer 10,the light emitting layer 30, and the second semiconductor layer 20. Byperforming this polishing step, the flatness of the surface of theworkpiece is improved.

Subsequently, as shown in FIGS. 3 and 6C, the nitride semiconductorlayer 10 s is divided in dimensions for each semiconductor lightemitting device (step S150). The example of FIG. 6C illustrates portionscorresponding to two semiconductor light emitting devices. Here, FIG. 6Cis depicted by vertically reversing the state shown in FIG. 6B.

Furthermore, a surface unevenness 10 u is formed at the surface of thefirst semiconductor layer 10 (the surface of the first semiconductorlayer 10 opposite to the light emitting layer 30). The surfaceunevenness 10 u is formed by treatment with e.g. a strong alkalineaqueous solution. The strong alkaline aqueous solution is e.g. anaqueous solution including at least one of potassium hydroxide andsodium hydroxide. The temperature of this treatment is e.g. 60° C. ormore and 80° C. or less.

As shown in FIG. 7A, a protective layer 80 covering the side surface andpart of the upper surface of the nitride semiconductor layer 10 s isformed.

As shown in FIG. 7B, a translucent layer 85 is formed on the surfaceunevenness 10 u of the first semiconductor layer 10.

As shown in FIG. 7C, an n-side electrode 10 e is formed on the region ofthe first semiconductor layer 10 where the translucent layer 85 is notprovided. A second substrate electrode 70 e is formed on the surface ofthe second substrate 70 opposite to the nitride semiconductor layer 10s.

Subsequently, the second substrate 70 (as well as the first barriermetal layer 15) is divided in the region between the semiconductor lightemitting devices. In this singulation (chip formation) step, methodssuch as laser scribing and laser dicing can be used.

Thus, the semiconductor light emitting device 110 is fabricated.

FIG. 8 is an electron micrograph image illustrating the method formanufacturing a semiconductor light emitting device according to thefirst embodiment.

More specifically, this figure is a scanning electron micrograph (SEM)image of a cross section of the first substrate 50 and the nitridesemiconductor layer 10 s midway during the process for manufacturing thesemiconductor light emitting device 110.

This example shows a cross-sectional SEM micrograph of the state (e.g.,the state of FIG. 4C) after the buffer layer 60, the first semiconductorlayer 10, the light emitting layer 30, and the second semiconductorlayer 20 are sequentially formed on the major surface 50 a of the firstsubstrate 50.

As seen from FIG. 8, a thin film 65 is formed on the inner wall surfaceof the depression 50 d of the unevenness 50 u of the first substrate 50.This thin film 65 includes the same material as at least part(specifically, the buffer layer 60) of the nitride semiconductor layer10 s. A cavity 50 c is left in the space inside the depression 50 d.

The lower surface of the portion (first portion 61) of the nitridesemiconductor layer 10 s facing the depression 50 d of the firstsubstrate 50 is flat and parallel to the major surface 50 a. Thus, inthe embodiment, the step for forming the nitride semiconductor layer 10s (step S110) includes causing at least part of the lower surface of theportion (first portion 61) of the nitride semiconductor layer 10 sfacing the depression 50 d to be parallel to the major surface 50 a ofthe substrate 50.

Thus, the lower surface of the portion (first portion 61) facing thedepression 50 d is made parallel to the major surface 50 a. Hence, theflatness of the surface of the nitride semiconductor layer 10 s afterseparation of the first substrate 50 is improved. This facilitatesflattening (e.g., the polishing step) of the nitride semiconductor layer10 s.

The position along the Z-axis of the lower surface of the first portion61 is substantially equal to the position along the Z-axis of the lowersurface of the second portion 62. That is, in the step for forming thenitride semiconductor layer 10 s (step S110), the position along theZ-axis (the axis perpendicular to the major surface 50 a) of the lowersurface of the portion (first portion 61) of the nitride semiconductorlayer 10 s facing the depression 50 d is made substantially equal to theposition along the Z-axis of the lower surface of the portion (secondportion 62) of the nitride semiconductor layer 10 s facing theprotrusion 50 p.

Thus, as viewed from the first substrate 50, the height of the firstportion 61 is made equal to the height of the second portion 62. Hence,for instance, the flatness of the surface of the nitride semiconductorlayer 10 s is improved, which facilitates e.g. the polishing step.

In the semiconductor light emitting device 110 manufactured by themanufacturing method according to the embodiment, damage to thesemiconductor layer in removing the growth substrate is suppressed.Thus, for instance, high light emission efficiency is achieved, and thereliability is improved.

FIGS. 9A to 9D, and 10A to 10C are sequential schematic sectional viewsillustrating a method for manufacturing a semiconductor light emittingdevice of a reference example.

As shown in FIG. 9A, the manufacturing method of the reference examplealso uses a first substrate 50 having a major surface 50 a provided withan unevenness 50 u.

As shown in FIG. 9B, a buffer layer 60 is formed on the major surface 50a. In the reference example, the inside of the depression 50 d of thefirst substrate 50 is filled with the same material as the buffer layer60. Thus, the cavity 50 c (as well as the thin film 65) is notsubstantially formed. That is, in the buffer layer 60, in addition tothe second portion 62 facing the protrusion 50 p, the first portion 61facing the depression 50 d is also in contact with the substrate 50.

Subsequently, as shown in FIGS. 9C, 9D, 10A, and 10B, a firstsemiconductor layer 10, a light emitting layer 30, a secondsemiconductor layer 20, a p-side electrode 20 e, and a first barriermetal layer 15 are formed and bonded to a second substrate 70.

Then, as shown in FIG. 10C, light Lr is applied to separate the firstsubstrate 50 from the nitride semiconductor layer 10 s (buffer layer60). At this time, the first portion 61 and the second portion 62 of thebuffer layer 60 are in contact with the first substrate 50. Hence, thefirst substrate 50 is not easily removed from the buffer layer 60. Thus,the intensity of light Lr required for separation is high. Hence, thenitride semiconductor layer 10 s is more prone to damage. Furthermore,the thin film 65 (as well as the cavity 50 c) is not provided in thedepression 50 d. Hence, the intensity of light applied to the firstportion 61 is high. That is, both the first portion 61 and the secondportion 62 of the nitride semiconductor layer 10 s are damaged.

Subsequently, by a process similar to that of the embodiment, thesemiconductor light emitting device of the reference example isobtained. In the semiconductor light emitting device of the referenceexample, the damage to the nitride semiconductor layer 10 s is greater.Hence, for instance, the light emission efficiency is low, and thereliability is low.

In contrast, the manufacturing method according to the embodimentsuppresses damage to the semiconductor layer in removing the growthsubstrate. Thus, for instance, a semiconductor light emitting devicewith high light emission efficiency and improved reliability isachieved.

As an alternative reference example, the nitride semiconductor layer 10s can be formed on a substrate with no unevenness 50 u. In thisreference example, the dislocation density in the nitride semiconductorlayer 10 s is high. In contrast, in the manufacturing method accordingto the embodiment, the nitride semiconductor layer 10 s is formed on themajor surface 50 a of the first substrate 50 having an unevenness 50 u.This reduces the dislocation density. According to the embodiment, ahigh quality crystal can be grown. Thus, high efficiency is achieved.

FIG. 11 is a schematic sectional view illustrating the configuration ofan alternative semiconductor light emitting device manufactured by themethod for manufacturing a semiconductor light emitting device accordingto the first embodiment.

As shown in FIG. 11, in the alternative semiconductor light emittingdevice 111 manufactured by the manufacturing method according to theembodiment, the side surface of the nitride semiconductor layer 10 s issloped. For instance, in the step described with reference to FIG. 6C,the nitride semiconductor layer 10 s is tapered. This tapered shape canbe obtained by appropriately controlling the processing condition forthe nitride semiconductor layer 10 s.

Thus, the manufacturing method according to the embodiment can bevariously modified.

FIGS. 12A to 12C are schematic views illustrating members used in themethod for manufacturing a semiconductor light emitting device accordingto the first embodiment.

FIGS. 12A and 12B are scanning electron micrograph images illustratingalternative first substrates 50 used in the manufacturing methodaccording to the embodiment. FIG. 12C is a schematic sectional viewillustrating the configuration of the first substrate 50 of thisexample.

As shown in FIGS. 12A and 12B, at the major surface 50 a of the firstsubstrate 50 used in this manufacturing method, a continuous depression50 d and a plurality of protrusions 50 p are provided. In this case, asviewed along the axis perpendicular to the major surface 50 a, thedepression 50 d surrounds each of the plurality of protrusions 50 p. Inthis example, the planar shape of the protrusion 50 p is circular.However, in the embodiment, the planar shape is arbitrary.

As shown in FIG. 12C, the upper surface of the protrusion 50 p has afirst width W1. The pitch along the axis perpendicular to the Z-axis oftwo adjacent protrusions 50 p is a second width W2. The width of thedepression 50 d along the axis connecting the centers of two adjacentprotrusions 50 p is a third width W3. The angle between the axis(Z-axis) perpendicular to the major surface 50 a of the first substrate50 and the slope of the protrusion 50 p is a slope angle θ.

In the example shown in FIG. 12A, the first width W1 is approximately 1μm. The second width W2 is approximately 5 μm. The third width W3 isapproximately 1.8 μm. The slope angle θ is approximately 30 degrees.

In the example shown in FIG. 12B, the first width W1 is approximately1.4 μm. The second width W2 is approximately 5 μm. The third width W3 isapproximately 1.9 μm. The slope angle θ is approximately 40 degrees.

In the embodiment, the area of the portion (second portion 62) of thenitride semiconductor layer 10 s facing the protrusion 50 p ispreferably smaller than the area of the portion (first portion 61) ofthe nitride semiconductor layer 10 s facing the depression 50 d. Thesecond portion 62 is a portion in contact with the first substrate 50.The first portion 61 is a portion separated from the first substrate 50.By making the area of the second portion 62 smaller than the area of thefirst portion 61, the first substrate 50 is easily separated from thenitride semiconductor layer 10 s. This further suppresses damage to thesemiconductor layer in removing the growth substrate.

In the case where the first substrate 50 includes a plurality ofdepressions 50 d, and in the case where the first substrate 50 includesa plurality of protrusions 50 p, at least one of the width along asecond axis (e.g., X-axis or Y-axis) parallel to the major surface 50 aof the top of the protrusion 50 p and the width along the second axis ofthe bottom of the depression 50 d is preferably 0.5 μm or more and 3 μmor less. Then, when the nitride semiconductor layer 10 s (e.g., bufferlayer 60) is formed on the major surface 50 a of the first substrate 50,the cavity 50 c can be stably formed.

In the first substrate 50, the average angle between the Z-axisperpendicular to the major surface 50 a and the side surface of theunevenness 50 u is preferably 20 degrees or more. Then, the cavity 50 ccan be stably formed while forming the thin film 65. Here, the sidesurface of the unevenness 50 u is e.g. the side surface of theprotrusion 50 p. Alternatively, the side surface of the unevenness 50 uis the side surface of the depression 50 d.

FIG. 13 is a schematic view illustrating a member used in the method formanufacturing a semiconductor light emitting device according to thefirst embodiment.

This figure is a schematic sectional view illustrating the configurationof an alternative first substrate 50 used in the manufacturing methodaccording to the embodiment.

In this example, the protrusion 50 p is continuous, and a plurality ofdepressions 50 d are provided. In this case, the angle (upper portionslope angle θ1) between the side surface of the upper portion of thedepression 50 d and the Z-axis (the axis perpendicular to the majorsurface 50 a) is preferably smaller than the angle (lower portion slopeangle θ2) between the side surface of the lower portion of thedepression 50 d and the Z-axis.

Then, when the nitride semiconductor layer 10 s is formed on the majorsurface 50 a of the first substrate 50, an appropriate amount of gas issupplied to the bottom portion of the depression 50 d. Thus, the cavity50 c can be stably formed while forming the thin film 65.

FIG. 14 is a schematic view illustrating a member used in the method formanufacturing a semiconductor light emitting device according to thefirst embodiment.

This figure is a schematic sectional view illustrating the configurationof an alternative first substrate 50 used in the manufacturing methodaccording to the embodiment.

In this example, the depression 50 d is continuous, and a plurality ofprotrusions 50 p are provided. In this case, the angle (upper portionslope angle θ3) between the side surface of the upper portion of theprotrusion 50 p and the Z-axis is preferably smaller than the angle(lower portion slope angle θ4) between the side surface of the lowerportion of the protrusion 50 p and the Z-axis.

Then, when the nitride semiconductor layer 10 s is formed on the majorsurface 50 a of the first substrate 50, an appropriate amount of gas issupplied to the bottom portion of the depression 50 d. Thus, the cavity50 c can be stably formed while forming the thin film 65.

Second Embodiment

In the embodiment, a first substrate 50 with a nitride semiconductorlayer 10 s formed thereon is prepared.

More specifically, a workpiece including a first substrate 50, a nitridesemiconductor layer 10 s including a light emitting layer 30, and a thinfilm 65 is prepared. The workpiece includes e.g. the stacked bodyincluding the first substrate 50 and the nitride semiconductor layer 10s, and the thin film 65 illustrated in FIG. 4B.

In the workpiece, the first substrate 50 has a major surface 50 aprovided with an unevenness 50 u. The nitride semiconductor layer 10 sis provided on the major surface 50 a. The nitride semiconductor layer10 s includes e.g. the buffer layer 60, the first semiconductor layer10, the light emitting layer 30, and the second semiconductor layer 20described above. That is, the workpiece may have the configurationillustrated in FIG. 4C.

The thin film 65 is provided on the inner wall surface of the depression50 d of the unevenness 50 u. The thin film 65 includes the same materialas at least part of the nitride semiconductor layer 10 s. The workpieceincludes a cavity 50 c provided in the space inside the depression 50 d.

For instance, as illustrated in FIG. 5A, the workpiece can furtherinclude a p-side electrode 20 e and a first barrier metal layer 15.

FIG. 15 is a flow chart illustrating the method for manufacturing asemiconductor light emitting device according to the second embodiment.

As shown in FIG. 15, the manufacturing method according to theembodiment includes a step for bonding the nitride semiconductor layer10 s of the workpiece to a second substrate 70 (step S120). Forinstance, the process described with reference to FIG. 10B is performed.

As shown in FIG. 15, the manufacturing method further includes a stepfor separating the first substrate 50 from the nitride semiconductorlayer 10 s by irradiating the nitride semiconductor layer 10 s withlight Lr via the first substrate 50 (step S130). That is, the processdescribed with reference to FIG. 10C is performed.

More specifically, the separating step (step S130) includes causing thethin film 65 to absorb at least part of the light Lr so that theintensity of light applied to the portion (first portion 61) of thenitride semiconductor layer 10 s facing the depression 50 d is madelower than the intensity of light applied to the portion (second portion62) of the nitride semiconductor layer 10 s facing the protrusion 50 pof the unevenness 50 u.

Hence, the embodiment can provide a semiconductor light emitting devicein which damage to the semiconductor layer in removing the growthsubstrate is suppressed.

As described above, in the manufacturing method, the nitridesemiconductor layer 10 s can include a buffer layer 60 provided betweenthe first substrate 50 and the light emitting layer 30, a firstsemiconductor layer 10 provided between the buffer layer 60 and thelight emitting layer 30, and a second semiconductor layer 20. The lightemitting layer 30 is located between the first semiconductor layer 10and the second semiconductor layer 20.

Thus, the manufacturing method according to the embodiment is applicableto manufacturing of a thin film type LED.

In the manufacturing method according to the embodiment, the firstsubstrate 50 having an unevenness 50 u is separated from the nitridesemiconductor layer 10 s while suppressing damage and peeling of thenitride semiconductor layer 10 s. Furthermore, the nitride semiconductorlayer 10 s has high crystal quality. Thus, the embodiment can provide asemiconductor light emitting device having high output and low cost.

Third Embodiment

The embodiment relates to a semiconductor light emitting device wafer.

FIG. 16 is a schematic sectional view illustrating the configuration ofa semiconductor light emitting device wafer according to the thirdembodiment.

As shown in FIG. 16, the semiconductor light emitting device wafer 210according to the embodiment includes a base member (first substrate 50),a nitride semiconductor layer 10 s, and a thin film 65. The firstsubstrate 50 has a major surface 50 a provided with an unevenness 50 u.The nitride semiconductor layer 10 s is provided on the major surface 50a. The nitride semiconductor layer 10 s includes a light emitting layer30. The thin film 65 is provided on the inner wall surface of thedepression 50 d of the unevenness 50 u, and includes the same materialas at least part of the nitride semiconductor layer 10 s. The nitridesemiconductor layer 10 s forms a cavity 50 c in the space inside thedepression 50 d.

By using the semiconductor light emitting device wafer 210, in the stepfor separating the first substrate 50 from the nitride semiconductorlayer 10 s by irradiating the nitride semiconductor layer 10 s withlight Lr via the first substrate 50, the thin film 65 is caused toabsorb at least part of the light Lr. Thus, the intensity of lightapplied to the portion (first portion 61) of the nitride semiconductorlayer 10 s facing the depression 50 d can be made lower than theintensity of light applied to the portion (second portion 62) of thenitride semiconductor layer 10 s facing the protrusion 50 p of theunevenness 50 u.

The semiconductor light emitting device wafer 210 according to theembodiment can realize a semiconductor light emitting device in whichdamage to the semiconductor layer in removing the growth substrate issuppressed.

As shown in FIG. 16, in the semiconductor light emitting device wafer210 according to the embodiment, the nitride semiconductor layer 10 scan include a buffer layer 60 provided between the first substrate 50and the light emitting layer 30, a first semiconductor layer 10 providedbetween the buffer layer 60 and the light emitting layer 30, and asecond semiconductor layer 20. The light emitting layer 30 is locatedbetween the first semiconductor layer 10 and the second semiconductorlayer 20.

Furthermore, the semiconductor light emitting device wafer 210 canfurther include e.g. a second semiconductor layer side electrode (e.g.,p-side electrode 20 e) described with reference to FIG. 4D.

Furthermore, the semiconductor light emitting device wafer 210 canfurther include e.g. a barrier metal film (e.g., first barrier metallayer 15) described with reference to FIG. 5A.

Furthermore, the semiconductor light emitting device wafer 210 canfurther include e.g. a second substrate 70 described with reference toFIG. 5B.

The embodiments can provide a method for manufacturing a semiconductorlight emitting device and a semiconductor light emitting device wafer inwhich damage to the semiconductor layer in removing the growth substrateis suppressed.

In the description, the “nitride semiconductor” includes semiconductorsof the chemical formula B_(x)In_(y)Al_(z)Ga_(1-x-y-z)N (0≦x≦1, 0≦y≦1,0≦z≦1, x+y+z≦1) of any compositions with the composition ratios x, y,and z varied in the respective ranges. Furthermore, the “nitridesemiconductor” also includes those of the above chemical formula furthercontaining Group V elements other than N (nitrogen), those furthercontaining various elements added for controlling various materialproperties such as conductivity type, and those further containingvarious unintended elements.

In the specification of the application, “perpendicular” and “parallel”refer to not only strictly perpendicular and strictly parallel but alsoinclude, for example, the fluctuation due to manufacturing processes,etc. It is sufficient to be substantially perpendicular andsubstantially parallel.

The embodiments of the invention have been described above withreference to examples. However, the invention is not limited to theseexamples. For instance, any specific configurations of variouscomponents such as the nitride semiconductor layer, buffer layer, firstsemiconductor layer, second semiconductor layer, light emitting layer,electrode, barrier metal layer (film), bonding layer, protective layer,translucent layer, and support substrate included in the semiconductorlight emitting device, and the first substrate used in the method formanufacturing a semiconductor light emitting device, are encompassedwithin the scope of the invention as long as those skilled in the artcan similarly practice the invention and achieve similar effects bysuitably selecting such configurations from conventionally known ones.

Further, any two or more components of the specific examples may becombined within the extent of technical feasibility and are included inthe scope of the invention to the extent that the purport of theinvention is included.

In addition, those skilled in the art can suitably modify and implementthe method for manufacturing a semiconductor light emitting device andthe semiconductor light emitting device wafer described above in theembodiments of the invention. All the methods for manufacturing asemiconductor light emitting device and the semiconductor light emittingdevice wafers thus modified are also encompassed within the scope of theinvention as long as they fall within the spirit of the invention.

Various other variations and modifications can be conceived by thoseskilled in the art within the spirit of the invention, and it isunderstood that such variations and modifications are also encompassedwithin the scope of the invention.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the inventions. Indeed, the novel embodiments described hereinmay be embodied in a variety of other forms; furthermore, variousomissions, substitutions and changes in the form of the embodimentsdescribed herein may be made without departing from the spirit of theinventions. The accompanying claims and their equivalents are intendedto cover such forms or modifications as would fall within the scope andspirit of the invention.

1. A method for manufacturing a semiconductor light emitting device,comprising: forming a nitride semiconductor layer including a lightemitting layer on a major surface of a first substrate, the majorsurface being provided with an unevenness having a depression and aprotrusion; bonding the nitride semiconductor layer to a secondsubstrate; and separating the first substrate from the nitridesemiconductor layer by irradiating the nitride semiconductor layer withlight via the first substrate, the forming the nitride semiconductorlayer including leaving a cavity in a space inside the depression of theunevenness while forming a thin film on an inner wall surface of thedepression of the unevenness, the thin film including a same material asat least a part of the nitride semiconductor layer, the nitridesemiconductor layer including a first portion facing the depression anda second portion facing the protrusion, and the separating includingcausing the thin film to absorb at least a part of the light so that anintensity of the light applied to the first portion is made lower thanan intensity of the light applied to the second portion.
 2. The methodaccording to claim 1, wherein the forming the nitride semiconductorlayer includes causing at least a part of a lower surface of the firstportion to be parallel to the major surface.
 3. The method according toclaim 1, wherein the protrusion is continuous, and the depression isprovided in a plurality, and an angle between a side surface of an upperportion of the depression and a first axis perpendicular to the majorsurface is smaller than an angle between a side surface of a lowerportion of the depression and the first axis.
 4. The method according toclaim 1, wherein an average angle between a first axis perpendicular tothe major surface and a side surface of the unevenness is 20 degrees ormore.
 5. The method according to claim 1, wherein at least one of awidth along a second axis parallel to the major surface of top of theprotrusion and a width along the second axis of a bottom of thedepression is 0.5 micrometers or more and 3 micrometers or less.
 6. Themethod according to claim 1, further comprising: reducing a thickness ofthe nitride semiconductor layer after the separating.
 7. The methodaccording to claim 1, wherein an area of the second portion is smallerthan an area of the first portion.
 8. The method according to claim 1,wherein the forming the nitride semiconductor layer includes: forming abuffer layer including a nitride semiconductor on the first substrate;forming a first semiconductor layer on the buffer layer, the firstsemiconductor layer including a nitride semiconductor and having a firstconductivity type; forming the light emitting layer on the firstsemiconductor layer; and forming a second semiconductor layer on thelight emitting layer, the second semiconductor layer including a nitridesemiconductor and having a second conductivity type different from thefirst conductivity type.
 9. The method according to claim 8, wherein thebuffer layer includes GaN.
 10. The method according to claim 8, whereina thickness of the buffer layer is 0.5 micrometers or more and 5micrometers or less.
 11. The method according to claim 1, wherein thethin film includes a same material as at least a part of the nitridesemiconductor layer.
 12. The method according to claim 1, wherein thethin film includes GaN.
 13. The method according to claim 1, wherein thefirst substrate is sapphire or SiC.
 14. The method according to claim 1,wherein the light is KrF laser light.
 15. A method for manufacturing asemiconductor light emitting device, comprising: bonding a nitridesemiconductor layer of a workpiece to a second substrate, the workpieceincluding: a first substrate having a major surface provided with anunevenness having a depression and a protrusion; the nitridesemiconductor layer provided on the major surface and including a lightemitting layer, the nitride semiconductor layer including a firstportion facing the depression and a second portion facing theprotrusion; a thin film provided on an inner wall surface of thedepression of the unevenness and including a same material as at least apart of the nitride semiconductor layer; and a cavity provided in aspace inside the depression; and separating the first substrate from thenitride semiconductor layer by irradiating the nitride semiconductorlayer with light via the first substrate, the separating includingcausing the thin film to absorb at least a part of the light so that anintensity of the light applied to the first portion is made lower thanan intensity of the light applied to the second portion.
 16. The methodaccording to claim 15, wherein the nitride semiconductor layer includes:a buffer layer provided between the light emitting layer and the firstsubstrate and including a nitride semiconductor, a first semiconductorlayer of a first conductivity type provided between the buffer layer andthe light emitting layer and including a nitride semiconductor, and asecond semiconductor layer of a second conductivity type different fromthe first conductivity type and including a nitride semiconductor, thelight emitting layer being disposed between the first semiconductorlayer and the second semiconductor layer.
 17. The method according toclaim 16, wherein the buffer layer includes GaN.
 18. The methodaccording to claim 16, wherein a thickness of the buffer layer is 0.5micrometers or more and 5 micrometers or less.
 19. The method accordingto claim 15, wherein the first substrate is sapphire or SiC.
 20. Asemiconductor light emitting device wafer comprising: a base memberhaving a major surface provided with an unevenness having a depression;a nitride semiconductor layer provided on the major surface andincluding a light emitting layer; and a thin film provided on an innerwall surface of the depression of the unevenness and including a samematerial as at least a part of the nitride semiconductor layer, thenitride semiconductor layer forming a cavity in a space inside thedepression.